Agoseris aurantiaca var. purpurea

(A. Gray) Cronquist

Rhodora 50: 33. 1948.

Common names: Colorado Plateau agoseris
Basionym: Macrorhynchus purpureus A. Gray Mem. Amer. Acad. Arts, n. s. 4: 114. 1849
Synonyms: Agoseris arizonica (Greene) Greene Agoseris attenuata Rydberg Agoseris aurantiaca subsp. purpurea (A. Gray) G. W. Douglas Agoseris confinis Osterhout Agoseris frondifera (Pursh) Rafinesque Agoseris glauca var. cronquistii S. L. Welsh Agoseris graminifolia Greene Agoseris longirostris (A. Gray) Greene Agoseris purpurea Rydberg Agoseris purpurea var. arizonica (Greene) G. L. Wittrock Agoseris roseata Agoseris rostrata
Treatment appears in FNA Volume 19. Treatment on page 328. Mentioned on page 327.

Leaf blades: margins usually dentate to laciniately pinnatifid, rarely entire, faces mostly glabrous and often glaucous. Peduncles mostly longer than leaves at flowering, glabrate or apically ± villous to lanate. Phyllaries ± stramineous proximally, green, often purple-black blotched or spotted, or with a purple-black midstripes, rarely nearly all black, usually ovate or obovate, sometimes lanceolate, subequal to unequal at flowering, margins ± ciliate, especially distally, faces glabrous or slightly pubescent basally or medially; outer mostly glabrous adaxially. Corollas usually orange or yellow, sometimes pinkish, subequal to or surpassing inner phyllaries. Cypselae: bodies ± gradually tapered to beaks, ribs ± weakly and uniformly ridged (not thickened distally). 2n = 18, 34, 36.

Phenology: Flowering Jun–Sep.
Habitat: Moist, subalpine meadows and forests to alpine tundra, often disturbed areas
Elevation: 1800–3600 m



Ariz., Colo., Nev., N.Mex., Utah, Wyo.


Variety purpurea is known mainly from the Colorado Plateau and southern Rocky Mountains. The two varieties are partially sympatric in the mountains of Colorado, Utah, southern Wyoming, and northern New Mexico, var. aurantiaca occurring only at very high elevations in that region. Wherever var. purpurea and var. aurantiaca occur together, they intergrade. Hybrids between var. purpurea and A. glauca or A. parviflora occur. One hybrid has been named (as a species): Agoseris aurantiaca var. purpurea × A. glauca var. dasycephala (= A. ×montana Osterhout) occurs sporadically at high elevations in the Rocky Mountains of Colorado.

Variety purpurea tends to exhibit a higher frequency of yellow-flowered populations than var. aurantiaca. Plants of var. purpurea from the Rocky Mountains usually have orange corollas; those from the plateaus of southern Utah and northern Arizona often have yellow corollas. These more southwestern populations have been called A. arizonica (or A. purpurea var. arizonica); the two regional phases cannot be adequately separated and their segregation is arbitrary.

Selected References


Lower Taxa

Gary I. Baird +
(A. Gray) Cronquist +
Macrorhynchus purpureus +
Colorado Plateau agoseris +
Ariz. +, Colo. +, Nev. +, N.Mex. +, Utah +  and Wyo. +
1800–3600 m +
Moist, subalpine meadows and forests to alpine tundra, often disturbed areas +
Flowering Jun–Sep. +
Illustrated +  and Endemic +
Agoseris arizonica +, Agoseris attenuata +, Agoseris aurantiaca subsp. purpurea +, Agoseris confinis +, Agoseris frondifera +, Agoseris glauca var. cronquistii +, Agoseris graminifolia +, Agoseris longirostris +, Agoseris purpurea +, Agoseris purpurea var. arizonica +, Agoseris roseata +  and Agoseris rostrata +
Agoseris aurantiaca var. purpurea +
Agoseris aurantiaca +
variety +